BlackRock Municipal Income Investment Trust (the Trust) is a non-diversified, closed-end management investment company. The Trust's investment objective is to provide shareholders with current income exempt from regular Federal income tax and Florida intangible personal property tax. The Trust invests at least 80% of its assets in municipal bonds that are investment grade quality. The Trust may invest up to 20% of its total assets in municipal bonds that are rated, at the time of purchase, Ba/BB or B by Moody's Investor Service, Inc. (Moody's), Standard & Poor's (S&P) or Fitch, Inc. (Fitch). The Trust may invest directly in such securities or synthetically through the use of derivatives. BlackRock Advisors, LLC is the Trust's investment advisor, an indirect, wholly owned subsidiary of BlackRock, Inc. BlackRock Financial Management, Inc., is the Trust's sub-advisor.